Neutrophil regulation of splanchnic blood flow after hemorrhagic shock

This study examines the hypothesis that neutrophils impair splanchnic blood flow during resuscitation from hemorrhage by inhibiting the release of the compensatory vasodilator PGI2 from the bowel. Resuscitation from hemorrhagic shock is associated with neutrophil infiltration into the intestine, reduced splanchnic perfusion, and reduced release of PGI2 from the intestine. Sprague-Dawley rats received either vinblastine (VIN) to deplete circulating neutrophils or normal saline (NS). These animals then underwent either hemorrhage and resuscitation (SK + R) or sham operation (SHAM). Superior mesenteric artery flow and splanchnic 6-keto PGF1a (metabolite of PGI2) release were measured. Superior mesenteric artery blood flow was significantly greater in VIN-treated animals sustaining SK + R than in those treated with NS (p < 0.05). Neutrophil depletion preserved 6-keto PGF1a release after SK + R, whereas 6-keto PGF1a release in the NS-treated, SK + R group was significantly reduced (p < 0.05). These data are compatible with the hypothesis that neutrophils may influence splanchnic perfusion after SK + R by inhibiting splanchnic PGI2 release.